The present invention relates to a method for processing heating wire of aquarium heater and an aquarium heater made by the method. Prior to sealing, the heating wire is previously coated with a thin insulative voltage-resistant and heat-resistant layer, whereby even though the outer protective skin of the heater is broken and water infiltrates therethrough, the insulative layer can still effectively avoid leakage of electricity.
It is known that infiltration of water and leakage of electricity often take place in the conventional aquarium heater. In manufacturing, in order to avoid leakage of electricity, the heater is watertightly wrapped by multiple layers of insulative skins. In a conventional single-tube type aquarium heater, the adjoining section between the heating wire and the metal conductive wire is possibly placed in the tube which is sealed by multiple watertight layers. FIG. 8 shows an elongated wire-shaped heater which is coated by multiple insulative skins to achieve a waterproof and insulative effect. FIG. 7 shows a manufacturing method for such heater, in which the heating wire sealed in the heater does not go through any insulative and waterproof processing prior to sealing. After connected with the metal conductive wire, the heating wire is directly placed into the tube or coated by the outer protective skin. Therefore, once the outer waterproof skin is damaged, water infiltration and leakage of electricity will take place.
As shown in FIG. 8, in the elongated wire-shaped heater, the heating wire is wound on a soft heat-resistant insulative wire material (such as fiber glass). Then the heating wire is electrically connected with the conductive wire via a terminal. Then the wires are coated with a protective silicone layer as an insulative skin. In coating procedure, the terminal is first wrapped by an inner high temperature-resistant silicone layer and then further coated with an outer silicone layer Accordingly, a bulge knot will be formed at the terminal. After a long period of use, the knot will suffer bending force and thermal expansion and contraction. Therefore, the protective skin tends to break. This leads to danger of infiltration of water and leakage of electricity. As a result, in use, the knot is prevented from being immerged in water so as to ensure safety.
In addition, in manufacturing, the heating wire and conductive wire must be connected with the terminals one by one and must be wrapped by two insulative layers. This is time-consuming and will increase manufacturing cost.